glycolysis

Question 1

step 1

Answer 1

• Glucose is phosphorylated to glucose-6-phosphate
• Consumption of 1 ATP
• One way reaction catalysed by hexokinase ( a transferase)
• Note: once phosphorylated, glucose becomes polar and is trapped in cell within phospholipid membrane

Question 2

step 2

Answer 2

• Glucose-6-phophate is isomerized to fructose-6-phosphate
• Not: substrate and product have the same molecular weight
• Reversible reaction catalysed by phosphoglucoisomerase (an isomerase)

Question 3

step 3

Answer 3

• Fructose-6-phosphate is phosphorylated to fructose-1, 6 biphosphate
• Consumption of 1 ATP
• One way reaction catalysed by phosphofructokinase (a transferase)

Question 4

step 4

Answer 4

• fructose-1,6-bisphosphate is
  cleaved to produce two threecarbon molecules
• • dihydroxyacetone phosphate
    (DHAP) and
• • glyceraldeyhyde-3-phosphate
    (G3P)
• Reversible reaction catalysed by
  Aldolase

Question 5

step 5

Answer 5

• Only glyceraldehyde-3-phosphate can proceed
  through the glycolytic pathway
• • Dihydroxyacetone phosphate is isomerised to glyceraldehyde-3-phosphate
• dihydroxyacetone phosphate –> glyceraldehyde-3-phosphate
• reversible reaction catalysed by triose phosphate isomerase
• All reactions from here will occur twice for the one input glucose Started glycolysis with 6C glucose, continue with 2 x 3C metabolites

Question 6

step 6

Answer 6

• Glyceraldehyde-3-phosphate is oxidised to 1,3-bisphosphoglycerate
• Requires 1 NAD+ and 1 Pi
• Coupled to reduction of NAD+ to NADH
• Reversible reaction catalysed by Glyceraldehyde-3- phosphate dehydrogenase
• Note Pi (inorganic phosphate) and NAD+ substrates

Question 7

step 7

Answer 7

• 1,3-bisphosphoglycerate is dephosphorylated to 3-phosphoglycerate
• One phosphate group is transferred to ADP, forming first ATP
• Substrate level phosphorylation
• Reversible reaction catalysed by Phosphoglycerate kinase

Question 8

step 8

Answer 8

• 3-phosphoglycerate is converted to 2-phosphoglycerate
• • The remaining phosphate group is transferred to a
    different carbon
• Reversible reaction catalysed by phosphoglyceromutase

Question 9

step 9

Answer 9

• 2-phosphoglycerate is converted to phosphoenolpyruvate (PEP)
• Reversible reaction catalysed by enolase (a dehydrogenase)

Question 10

step 10

Answer 10

• Phosphoenolpyruvate is dephosphorylated to pyruvate
• The phosphate group is transferred to ADP forming ATP
• Generation of second ATP
• One way reaction catalysed by pyruvate kinase